The present invention relates to a lens protection device, and more particularly to a removable cover device for a camera lens.
A camera lens protection device, or lens cover, or lens cap, protects a front surface of a photographic lens. The lens cover removes from the barrel during photographic use and attaches when not in use to protect the fragile outer-lens surface from damage. Various attempts to provide a lens cover or other such protection or barrier device suitable for protecting a camera lens include articulating lens caps that remain coupled to the lens barrel or camera body and rotate away from the front surface of the barrel lens or removable caps incorporating tensioning devices and release mechanisms.
One such articulating lens protection device includes U.S. Pat. No. 6,799,854 to Steiner on 5 Oct. 2004. The Steiner reference discloses a protective lens cap for binoculars. The lens cap includes a single articulating mechanism consisting of a pivot joint. This enables the lens to articulate from a substantially horizontal pivot axis to a substantially vertical pivot axis. Accordingly, the protective lens cap can be swung upwards from the closed condition about the substantially horizontal pivot axis and secured to the body. The Steiner lens cap includes an attachment that enclasps an outer edge of the lens cap by a crimp having pivot-bearing bolt molded integrally to form part of a pivot bearing. A joining piece includes a forked end to cooperate with the pivot bearing bolt to establish a bearing axis corresponding to a central longitudinal axis of the bearing bolt.
Another representative example of prior-art articulating lens covers adapted for use on cameras includes the disclosure of Motohashi et al. in U.S. Pat. No. 6,247,855 on 19 Jun. 2001. The Motohashi reference describes moving mechanism attached to a camera. The mechanism transfers linear motion along the optical axis to rotary motion adapted to rotate a lens cover about 180-degrees from a first position covering the front surface of the lens to a second position. The mechanism includes a cover open/close groove formed along the optical axis of the lens on both sides of a pedestal extending downward from the outer circumference of the lens barrel. Protrusions of a cover manipulation member engage the cover open/close groove so that the protrusions can slide freely along the optical axis of the lens. A cover manipulation member supports a lens protecting cover for opening or closing the face of the photographic lens and drives the lens protecting cover into the open or closed positions. Additionally, a spring assembly serves as a constraining member to force the cover into a closed position when the cover manipulation member presents the lens to the front of the barrel. A similar articulating structure is disclosed by Muroi et al. in U.S. Pat. No. 6,033,130 on 7 Mar. 2000.
Another example of an articulating lens cover includes the lens barrier device described in U.S. Pat. No. 6,672,777 to Kobayashi et al. on 6 Jan. 2004. The Kobayashi device includes a lens barrier movable between a position covering a front of a lens and a position withdrawn from the front of the lens. An engagement member engages a filter screw-thread provided by the barrel lens and a rotary shaft that enables the barrier to rotate about 180-degrees from the position covering the front of the lens the withdrawn position. A spring assembly provides sufficient pressure on the barrier device to selectively restrain the barrier in the covering position until a sufficient manual force is applied to deliberately rotate the barrier to the withdrawn position.
Although articulating lens devices of the prior art provide one advantage of permanently coupling a lens cover to the camera or lens barrel—ensuring that the lens cover can not be misplaced—such designs afford this advantage at considerable cost as measured by complexity of mechanisms, numbers of moving parts, and expense to manufacture and maintain.
The second type of lens protection devices of the prior art include removable caps that incorporate tensioning devices and release mechanisms. U.S. Pat. No. 4,600,278 to Saito issued on 15 Jul. 1986 represents a type of removable lens caps incorporating a locking member movable radially of the body of the cap. This conventional removable cap includes a disk-like body and locking member that is held to the body so as to be radially movable. A pair of support blocks mounts on the body in parallel relation to a radius. Each support block includes a retaining groove and guide surface, which guides sliding movement of engaging legs provided by the locking member. Compression springs cause the locking member to protrude into a screw thread provided by the barrel of the lens. To remove or insert the lens cap, a user must apply a force inward to the center of the disklike body. The locking member includes a feature that enables a user to insert a portion of the user's finger for this purpose.
Although the type of lens cover described by Saito protects the front end of a lens barrel, this design includes several parts, which must be carefully assembled. This design relies on springs to exert a force—and importantly—requires the barrel to provide a filter thread, which may not always be available Further, this design includes moving parts and a number of components, of which the movement of parts is necessary to successfully insert and remove the lens cap from the barrel. The number of parts along with tolerances between parts and wear induced on the parts results in a design that is both uneconomical to produce and prone to failure. Of particular concern, the tensioning spring members of this prior-art design are prone to premature failure, which renders the cap unable to remain in place and no longer functioning as a lens protection device.
Many of the prior-art attempts to provide a cover device for a camera lens do not work with larger lenses, such as large telephoto lenses equipped with a hood. A lens hood prevents unwanted light rays from entering the lens, reducing glare and ghost images. A lens hood, which is generally cylindrical or conical in shape, includes an internal screw-thread adapted to couple over the end of a barrel lens assembly, such as a telescopic lens for a camera. Once in place, the lens hood prevents known prior-art lens caps from mounting on the lens. One other limitation of a bag-type lens protection device for larger barrel lenses, which use a cloth or leather sack open on one end with a drawstring closure at the open end, includes imperfect sealing of the bag when the lens barrel is transported and, further, the bag cannot be used once the lens mounts to the camera.
Another problem common with the prior art lens caps include a practical difficulty of removing and inserting the lens cap when the hood is attached and the lens is in a shooting position, The deep void between the face of the hood and the face of the lens makes it impossible for many photographers to reach in and exert sufficient pressure on the typical radial mounted, spring-tensioning devices of the prior art. Further, articulating lens covers do not work at all with a hood. The articulating structure blocks and makes physically impossible to mount a hood to such a lens assembly.
Thus, there remains a need for a lens cap device that can be economically produced and that limits the number of components. Such a device, ideally, would not have moving parts, which are prone to wear and failure. Such a device should remain fast in position when protecting the lens, but be readily and easily removable when the lens is needed for use with a camera.